This invention relates to a method of manufacturing a liquid crystal panel and a gap adjusting apparatus therefor.
In general, a panel assembly (or cell) is used for manufacturing a liquid crystal panel. The panel assembly includes a pair of substrates located in opposition to each other with leaving a gap to define an internal space which is filled with liquid crystal. When an excess of the liquid crystal is filled into the internal space of the panel assembly, a gap between the substrates is expanded. Therefore, it is necessary to prevent the excess of the liquid crystal from being filled into the internal space or to discharge the excess of the liquid crystal from the internal space. These can be made by adjusting the gap within a proper range.
A first related method of manufacturing a liquid crystal panel uses pressing plates to press both faces of the panel assembly when or after the liquid crystal is filled into the internal space thereof. According to the method, the excess of the liquid crystal is prevented from being filled into the internal space or discharged from the internal space. Consequently, sealing a filling port of the panel assembly keeps the gap within the proper range after the pressing plates are taken away. Such a method is disclosed in Japanese Patent Application Publication (JP-A) No. H6-88951.
A second related method of manufacturing a liquid crystal panel uses a pressure difference between inside and outside of the panel assembly. According to the method, the excess of the liquid crystal is discharged from the internal space and thereby the gap is adjusted within the proper range. Such a method is disclosed in Japanese Patent Application Publication (JP-A) No. H7-20480 or No. 2000-347197.
A third related method of manufacturing a liquid crystal panel uses a vacuum packing bag and atmospheric pressure. When the vacuum packing bag is evacuated, the panel assembly placed therein is pressed by atmospheric pressure. As a result, the excess of the liquid crystal is discharged from the internal space and thereby the gap is adjusted within the proper range. Such a method is disclosed in Japanese Patent Application Publication (JP-A) No. H3-78724.
A fourth related method of manufacturing a liquid crystal panel uses a vacuum pump to draw the excess of the liquid crystal from the panel assembly. Such a method is disclosed in Japanese Patent Application Publication (JP-A) No. H7-318949.
These methods mentioned above have a common problem. That is, the excess of the liquid crystal discharged from the panel assembly adheres to an edge of the panel assembly around the filling port. The liquid crystal on the edge of the panel assembly must be wiped. This reduces manufacturing efficiency.